#!/usr/bin/env perl                                                   
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use strict;                                                           
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use warnings;                                                         
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sub say (_) {                                                         
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    print @_, "\n";                                                   
}                                                                     
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my @a = qw(1 2 3);                                                    
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# using implicit $_ does not work:                                    
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say foreach (@a);                                                     
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# ...and of course explicit $_ works.                                 
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say $_ foreach (@a);                                                  
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# works:                                                              
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say "uncle bob";
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Illegal character in prototype for main::say : _ at a.pl line 6.
Not enough arguments for main::say at a.pl line 13, near "say foreach 
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Malformed prototype for main::say: _ at a.pl line 16.
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